In a multicast Virtual Private Network (VPN), multicast transmission technologies are implemented based on a Multi-protocol Label Switching (MPLS) Layer-3 Virtual Private Network (L3VPN). The L3VPN is the VPN implemented using the Border Gateway Protocol (BGP) and MPLS extension technology and is constituted by a backbone network of an operator and sites. The sites are isolated and interconnect with each other via the backbone network. The VPN may be taken as a group of strategies, which are used to control connection among the sites.